1. Field
The subject disclosure relates generally to wireless communications, and more specifically to calibration techniques for devices operating in a wireless communication system.
2. Background
Wireless communication systems are widely deployed to provide various communication services; for instance, voice, video, packet data, broadcast, and messaging services may be provided via such wireless communication systems. These systems may be multiple-access systems that are capable of supporting communication for multiple terminals by sharing available system resources. Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, and Orthogonal Frequency Division Multiple Access (OFDMA) systems.
As digital communication technology has advanced, users have come to expect faster throughputs in the face of harsher conditions. As a result, requirements for digital communication systems have become harder to implement. Likewise, newer systems typically require tighter controls and higher fidelity than that provided for previously released systems. To accomplish this, these systems implement features such as high fidelity in digital-to-analog conversion, frequency translation, amplification and the like. In addition, where components cannot be made so precisely as to not require it, calibration and correction circuits, methods, and processes are used to correct for inaccuracies and imprecision.
Some digital communication systems send data at radio frequencies (“RF”) and have an I/Q (in-phase and quadrature) modulation and/or demodulation front-end. Gain and phase imbalances between the I and Q components of an I/Q modulator and demodulator in such a system can introduce in-band distortion. As a result, there is a need for calibration in such systems to reduce the effect of such imbalance.